Resonant sensors, or more generally resonators, are devices or systems that resonate at specific frequencies or exhibit resonant behavior. Moreover, when these resonant sensors are subjected to an input power, they oscillate. The amplitude of oscillation depends on the frequency of oscillation. For example, a resonant sensor will oscillate with greater amplitude when the frequency of oscillation coincides with any of its resonant frequencies. Depending on design choices or other factors, a resonant sensor may be electrically based and/or mechanically based (e.g., acoustic). Resonant sensors may be used to monitor a variety of physical quantities including temperature, humidity, pressure, and torque. For example, the temperature of an environment can affect the resonance frequency of a resonant sensor. In such an example, as the temperature of the environment changes, the mechanical properties of the materials included in the resonant sensor will change based on the temperature. This change in material properties corresponds to a change in resonance frequency, thus by determining the resonance frequency the temperature can be determined.
Resonant sensors may be implemented as microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS). In some cases, MEMS are referred to as micromachines and/or micro systems technology (MST) whereas NEMS are referred to as nanomachines and/or nano-systems technology. To monitor the response of such MEMS or NEMS, a sensor monitor is utilized. In some applications, the sensor monitor is a separate device or system that monitors the resonant sensor. The sensor monitor can measure a shift in resonance frequency of the resonant sensors. When a sensor monitor detects a shift in resonance frequency, the shift can be interpreted as a shift in the underlying physical quantity being measured (e.g., temperature, pressure, torque, etc.).
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Descriptors “first,” “second,” “third,” etc. are used herein when identifying multiple elements or components which may be referred to separately. Unless otherwise specified or understood based on their context of use, such descriptors are not intended to impute any meaning of priority or ordering in time but merely as labels for referring to multiple elements or components separately for ease of understanding the disclosed examples. In some examples, the descriptor “first” may be used to refer to an element in the detailed description, while the same element may be referred to in a claim with a different descriptor such as “second” or “third.” In such instances, it should be understood that such descriptors are used merely for ease of referencing multiple elements or components.